Eukaryotic Recombinases Duplicated After Divergence From Known Asgard Archaeal RadA: Implications for the Evolution of Sex During Eukaryogenesis
Bibliographic record
Abstract
The origin of meiotic sex was a key milestone in the evolution of the eukaryotic cell. The paralogous DNA recombinases Rad51 and meiosis-specific DMC1 are nearly universal among eukaryotes and have been used previously to trace the timing and origins of the meiotic machinery. Here we perform comparative genomics and phylogenetic analyses of Rad51 and DMC1 drawn from diverse eukaryotes with RadA recombinase sequences from a broad sampling of archaeal taxa, focusing on the recently sequenced diversity of Asgard archaeal taxa. We show that even with increased and new sampling, the eukaryotic Rad51 and DMC1 proteins still resolve separately from any archaeal RadA sequences. These findings suggest that the duplication of RadA into general and meiosis-specific paralogues occurred after the divergence of the eukaryotic progenitor and did not evolve at an earlier stage. These findings raise the important question of how the evolution of meiotic sex was linked to genome size expansion and the acquisition of the mitochondrial endosymbiont in early eukaryotes.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".